“Security theater“ is a rhetorical device for claiming something doesn’t help, without actually having to bother providing any evidence for your claim.
The evidence, from the studies you have referenced, is that cloth masks prevent an infected person from breathing covid directly into the face of an uninfected person. That is hygiene, not theater.
Do you have a logical objection to running a school with good ventilation and cloth masks? The classroom HEPA filter prevents aerosol buildup, and the mask prevents direct person to person infection. Much better than putting N95 masks on kids, and less community spread than going totally mask free.
So you are down to "directly into the face of an uninfected person". that's your standard now? Wow, look at how far we've come. From masks are better than vaccines to "directly into the face of an uninfected person".
You know, as well, that Spain, France, Italy and (on public transportation) Germany don't allow cloth masks? You know as well that none of these countries require masking of young children?
As usual, it comes down to a cost/benefit analysis. The benefit of cloth masks is very small. Again, we're down to "directly into the face of an uninfected person". The costs, particularly when it comes to kids, are high, and on top of that we have an alternative from the study (which is better ventilation). In places were better ventilation isn't a possibility, we need to have a serious discussion of what we need to do as a society. But we can't have that discussion until you realize that cloth masks are the equivalent of a bandaid on the problem, and a clear explanation for why the real world results (again see Hawaii, Israel, Iceland), don't match your preferred theories.